A man has told court how he warned a neighbour not to use a boiler he had fitted as it had a gas leak.

Hours later she was dead.

Linda Frost died from carbon monoxide poisoning after her unqualified friend fitted a “dangerous” bathroom boiler in her Leysdown chalet, a court heard.

The 61-year-old collapsed while taking a shower and was found unconscious. She was taken to hospital but died soon afterwards.

The boiler was fitted by Terry Blackwell, a next-door neighbour at Coronation Chalet Park in Coronation Drive, who is denying involuntary manslaughter at a trial this week.

Maidstone Crown Court heard Mrs Frost bought the two-bedroom bungalow with her sister and became friends with Blackwell and his wife Mary.

Prosecutor Philip Bennetts said Mrs Frost’s bathroom boiler and kitchen boiler stopped working in the winter of 2012.

Blackwell fitted a new kitchen boiler.

In April last year, Mrs Frost told her father William Worrell that Blackwell had fitted a new bathroom boiler for her.

“It was very dangerous as there was no flue, just a hole in the asbestos type chalet wall with an old balanced flue still in place" - Gas engineer Michael Minnet

He asked what kind of flue it had and was told it did not have one. Mrs Frost said the old flue had been taken out and Blackwell had boarded over the hole.

“She said that he had drilled holes in the board for ventilation,” Mr Bennetts told the jury.

Mr Worrell advised her to make sure it was tried out properly before she used it as he did not like the idea of it not having a flue.

She replied: “Yes, I’ll remember that.” She did not say she had been told not to use the boiler.

Mrs Blackwell went to the chalet on April 13 and found Mrs Frost had collapsed in the shower.

An ambulance was called and Mrs Blackwell and neighbours gave Mrs Frost CPR until paramedics arrived.

She was taken to Medway hospital at about 9.15am. She was pronounced dead at 12.50pm.

The cause of death was hypoxic brain injury due to inhalation of carbon monoxide.

Mr Bennetts said Blackwell, who denies the charge, bought the “6L portable gas LPG propane tankless hot water boiler” on eBay.

He added that Blackwell, of Hartland Forest, Woolsery, Devon, was not registered with the Gas Safe Register.

When arrested, he declined to answer most questions. Asked about the origin of the boilers, he said the police should know where they were bought.

"There must have been an obvious and serious risk of death" - Philip Bennetts, prosecuting

Mr Bennetts said Blackwell owed Mrs Frost a duty of care. He was not qualified or registered to install such an appliance.

“You may consider Terry Blackwell’s conduct is capable of being described as reprehensible,” he told jurors. “There must have been an obvious and serious risk of death.”

Gas engineer Michael Minnet examined the boiler after the tragedy and declared that type should not be fitted as it was only supposed to be used for five minutes because there was no flue and it needed ventilation.

Instructions on the side of the boiler clearly stated it should be fitted outside the bathroom.

“The boiler was doing a job it was not designed for and no safety conscious engineer would fit it that way,” he said.

“It was very dangerous as there was no flue, just a hole in the asbestos type chalet wall with an old balanced flue still in place.

“The fumes generated from this hole would not go out of this hole but straight into the room.”

Blackwell claimed in evidence he warned Mrs Frost not to use the boiler until he had fixed a gas leak in it.

He said he started work on it in the morning and did not notice a label on the side of the boiler which said “gas type NG (natural gas)”.

“I didn’t know I was connecting the wrong boiler to the wrong gas supply,” he admitted.

He also did not realise, he said, that the boiler should not be fitted in the bathroom.

“The advert on eBay says ‘outside/inside bathroom’,” he said. “I presumed you could put it inside.”

He put water through the boiler to make sure it did not have a leak. He then discovered there was a gas leak.

“I tightened it as much as I could,” he continued. “It didn’t make any difference. It was getting late. Dinner was nearly ready so I stopped.

“I told Linda: ‘There is a gas leak there. You can’t use it. I have done enough today. I will finish it tomorrow.’ I turned the gas off and said she couldn’t use it.”

Mrs Frost went to Blackwell’s chalet for dinner. He told her again she could not use the boiler, he claimed.

He and his wife heard Mrs Frost say to her grandson Thomas Standing on the phone: “My boiler’s up. I can have a shower tomorrow.”

Blackwell claimed his wife said loudly: “No, you can’t. It’s not ready.” She went to her chalet at about 10.45pm.

The next morning Mrs Blackwell went to see her. She returned shouting: “Lin’s unconscious on the floor.”

“I rushed across,” said Blackwell, “She was slumped down in the shower as if she had fallen in. She was half in and half out. I phoned the ambulance service immediately.

“My wife was upset. She was in shock. They were good friends.”

Prosecutor Philip Bennetts QC questioned whether he had experience of fitting such boilers. Blackwell replied: “Only cookers.”

Asked if he accepted he was negligent in installing the boiler, he said: “I hadn’t completed the installation. I accept I was negligent in not looking at the labels.”

He admitted he did not read the special note of caution on the side of the boiler that it should be installed in a well-ventilated place outside the bathroom.

“I read the instructions in the manual,” he said.

Blackwell said he was going to buy a new copper pipe in the morning and fix the gas leak.

Mr Bennetts told him: “You are just not telling the truth about this, are you?”

Blackwell insisted he was.

He added: “I didn’t tell her what the consequences would be if she used it. I presumed she would know what the consequences are.

“I did not put a notice on it that it should not be used. I didn’t further test it and tell her it was fine.

“I did tell her I wasn’t qualified. She couldn’t afford to pay someone to fit it. I paid her utility fees for the year and the boiler so she didn’t have any expense.”

The trial continues.